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Pratt & Whitney PW4000
Pratt & Whitney PW4000
Pratt & Whitney PW4000
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PW4000
The 112-inch (2.8 m) fan diameter PW4098 used on the Boeing 777
TypeTurbofan
National originUnited States
ManufacturerPratt & Whitney
First runApril 1984[1]
Major applications
Manufactured1984–present
Number built2,500 (June 2017)[2][needs update]
Developed fromPratt & Whitney JT9D
Developed intoEngine Alliance GP7000

The Pratt & Whitney PW4000 is a family of dual-spool, axial-flow, high-bypass turbofan aircraft engines produced by Pratt & Whitney as the successor to the JT9D. It was first run in April 1984, was FAA certified in July 1986, and was introduced in June 1987. With thrust ranging from 50,000 to 99,040 lbf (222 to 441 kN), it is used on many wide-body aircraft.

Development

[edit]

The 52,000–62,000 lbf (230–275 kN), 94 in (2.4 m) -fan PW4000 made its first run in April 1984, was FAA certified in July 1986, and was introduced in June 1987. It powers the Airbus A300-600 and Airbus A310-300, Boeing 747-400 and 767-200/300, and McDonnell Douglas MD-11 widebodies.[1]

Development of the 64,000–68,000 lbf (280–300 kN), 100 in (2.5 m)-fan version began in December 1991 for the Airbus A330, was FAA certified in August 1993, and made its first flight two months later. It received 90min Extended-range Twin-engine Operations (ETOPS) approval at introduction in December 1994, and 180min ETOPS approval in July 1995. In January 2000, it was the A330 market leader with more than half of the installed base and one million hours, more than twice that of each competitor.[1] The Advantage 70 upgrade package for the PW4168A, which powered around one-third of the active Airbus A330 fleet, was launched at the 2006 Farnborough Airshow, increasing thrust to 70,000 lbf (311 kN), and reducing fuel burn by about 1.2% as well as overall operating costs by as much as 20%.[3]

A PW4074 on an ANA 777-200 under maintenance with the fan doors open, showing the fan disk inside the inlet cowling at the front of the engine

For the Boeing 777, the 84,000–98,000 lbf (370–440 kN), 112 in (2.8 m)-fan version development began in October 1990, achieved 100,000 lbf (440 kN) in May 1993, and was approved for 180min ETOPS at service entry in June 1995.The 777 launch engine, it entered service on 7 June 1995, with United Airlines. The 90,000 lbf (400 kN) PW4090 entered service in March 1997. The 98,000 lbf (440 kN) PW4098 received FAA certification in July 1998 and was introduced on the Boeing 777-300 in September 1999 but was a few years later discontinued due to core temperature problems and fuel burn that was not appealing to airlines.[1]

In 2000, over 2,000 PW4000 engines had accumulated over 40 million hours of service with 75 operators.[1] In 30 years between June 1987 and 2017, more than 2,500 engines have been delivered, logging more than 135 million flight hours.[2]

Design

[edit]
PW4077 titanium-bladed fan section with containment ring in the United Airlines maintenance facility at SFO

The PW4000 has a dispatch reliability rate of 99.96% and is approved for ETOPS 180. The average engine stays on wing 13,500 flight hours before a shop visit (a Shop Visit Rate of 0.073 per thousand hours). It is claimed to be cumulatively 3.4 dB quieter than other engines in its class.[1]

Like other modern aircraft power plants, it has a Full Authority Digital Engine Control (FADEC), for better fuel economy and reliability.[4] Furthermore, single-crystal alloys allows higher temperature capability and PW's Floatwall combustor liners improve durability and maintainability.[1] Also, the Talon ("Technology for Affordable Low NOx") single-row combustor improves fuel-air mixing, for over 10% better NOx, CO, and HC emissions.[1]

Variants and applications

[edit]
A -94 powering the Boeing 767 with 38 fan blades
A -100 powering the Airbus A330 with 34 fan blades
A -112 powering the Boeing 777 with 22 fan blades

The PW4000 series engine family uses a numbering systematic with the last three digits (PW 4XYZ) as identification of the application and thrust power:

  • X describes the aircraft manufacturer for which the engine is approved. A "0" stands for Boeing; "1" for Airbus; and "4" for the McDonnell Douglas MD-11.
  • YZ denotes the certified thrust in US pounds (lbf) in pro-mile fraction.

Example: A PW4090 identifies a PW4000 series engine certified for Boeing (777-200ER) and has a certified thrust of 90,000 lbf.

A PW4000-94 engine on Boeing 767-300ER

PW4000-94

[edit]

Variants: PW4052, PW4056, PW4060, PW4062, PW4062A, PW4152, PW4156A, PW4156, PW4158, PW4460 and PW4462.
Thrust range: 231–276 kN (52,000 lbf – 62,000 lbf)[5]
Applications:

A PW4000-100 on Airbus A330-200

PW4000-100

[edit]

Variants: PW4164, PW4168, PW4168A and PW4170.
Thrust range: 287–311 kN (64,500 lbf – 70,000 lbf)[6]
Applications: the engine variants are designed exclusively for Airbus A330-200 and -300 (the first generation A330 or A330ceo) (Note that this does not include the A330neo: -800 or -900, which are powered exclusively by Trent 7000, nor the BelugaXL: A330-700, which are powered exclusively by Trent 700).

The PW4000-112 on the original Boeing 777-200; these were replaced with Rolls-Royce Trent 800 engines when it entered commercial service as B-HNL

PW4000-112

[edit]

Variants: PW4074/74D, PW4077/77D, PW4084/84D, PW4090 and PW4098.
Thrust range: 329–436 kN (74,000 lbf – 98,000 lbf)[7]
Applications: the engine variants are designed exclusively for Boeing 777-200, -200ER, -300 (the first generation 777 or 777 Classics). (Note that this does not include the second generation 777: -200LR, -300ER or F which are powered exclusively by the GE90, nor the 777X: -8, -8F, or -9, which are powered exclusively by GE9X).

Accidents and incidents

[edit]
UAL1175 PW4077 fan blade root section fracture surface showing metal fatigue
Damage to hollow fan blades from UA328, fracture surface near hub at top of photo

Involving PW4000-112 series

[edit]
17 March 2003, United Airlines Flight 842
A PW4090 failed bearing caused the engine loss and the diversion to Kona, Hawaii, of a Boeing 777-200ER bound from Auckland, New Zealand, to Los Angeles. At 190 minutes this was the longest single-engine diversion on record at the time. [8][9][10]
27 May 2016, Korean Air Flight 2708
A PW4090 uncontained turbine failure caused an aborted take-off,[11][12] on a Boeing 777-300 at Tokyo-Haneda Airport.[13]
13 February 2018, United Airlines Flight 1175
A PW4077 fan blade failure caused significant engine damage to a Boeing 777-200 on descent into Honolulu from San Francisco.[14] Routine fan blade inspection in 2005 and 2010 had shown a crack in the blade's metal structure but insufficiently trained inspectors had confused it for a defect in the paint. [15][16] In 2019, an airworthiness directive mandated recurring engine inspections based on usage cycles.[17]
4 December 2020, Japan Airlines Flight 904
A PW4074 engine had a fan blade failure and associated engine cowl damage as the Boeing 777-200 was climbing out of Okinawa.[18] As of March 2021 the investigation is ongoing.
20 February 2021, United Airlines Flight 328
Boeing 777-200's right hand PW4077-112 had a blade failure shortly after taking off from Denver, causing significant engine damage.[19][20] Two fan blades had broken off: one had suffered metal fatigue and possibly chipped another blade which also broke off.[21] The failed blade was compliant with the inspection interval set by the FAA following the 2018 incident. The FAA grounded the affected 777s and issued an emergency Airworthiness Directive on 23 February, requiring a Thermal Acoustic Inspection (TAI) of the -112 fan blades before next flight.[22][23] Japanese authorities and the UK's CAA followed suit,[19] grounding 69 in-service and 59 in-storage Boeing 777s.[24][25] Most carriers had voluntarily grounded the aircraft before, except South Korea's Jin Air's four aircraft.[citation needed] As of March 2021 the investigation is ongoing.[citation needed]

Involving PW4000-100 series

[edit]
6 May 2014, Vietnam Airlines VN-A371
Uncontained failure of a PW4168A low-pressure turbine's stage four causing an Airbus A330 rejected take-off at Melbourne Airport in Australia.[26]
13 February 2018, Delta Air Lines Flight 55
PW4168 fire in an Airbus A330-200 climbing from Lagos (Nigeria) at 2000 feet.[27]
18 April 2018, Delta Air Lines Flight 30
Airbus A330-323's PW4168A fire after takeoff from Atlanta,[28][29] investigated by the NTSB and the French BEA.[30]

Involving PW4000-94 series

[edit]
7 June 2017, Delta Air Lines flight 276
Metallic debris in a PW4056 tailpipe and a 360-degree crack in the LP turbine case just forward of the rear flange caused a Boeing 747-400 cruising at FL320 to return to Tokyo Narita.[31] All of the HPC airfoils from the 5th to the 15th stage were damaged with nicks, dents, and tears to the leading and trailing edges and/or were broken off at various lengths above the blade root platforms. The HPT and LPT also had extensive damage, and the LPT case had a 360° split in line with the 6th stage turbine rotor.[31] The NTSB reports 38 airfoil fractures of the 5th stage compressor blade before the part was updated.[31]
20 February 2021, Longtail Aviation Flight 5504
Boeing 747-412BCF PW4056 failure shortly after taking off from Maastricht Aachen Airport : falling turbine blades slightly injured two persons on the ground, the airplane was able to land safely at Liège Airport.[32][33][34][35]
28 March 2022, United Airlines Flight 134
Boeing 767 powered by Pratt & Whitney PW4060 engines experienced fan blade separation on the right-side (number 2) engine during a flight from New York to Zürich. The incident occurred over the Atlantic Ocean. The aircraft diverted to Shannon, Ireland, and landed safely with 123 persons on board.[36]

Specifications

[edit]

The PW4000 is produced in three distinct models, with differing LP systems to address different thrust needs.

Variant -94[37] -100[38] -112[39]
Type Two spool high bypass ratio Turbofan
Length 153.6 in (390 cm) 167.2 in (425 cm) 190.4 in (484 cm)
Weight 9,420 lb
4,273 kg 		12,900 lb
5,851 kg 		15,095–15,741 lb
6,847–7,140 kg 		16,260 lb
7,375 kg
Compressor 1 fan, 4 LP, 11 HP 1 fan, 5 LP, 11 HP 1 fan, 6 LP, 11 HP 1 fan, 7 LP, 11 HP
Combustor Annular
Turbine 2 HP, 4 LP 2 HP, 5 LP 2 HP, 7 LP
Thrust 50,000–62,000 lbf
222–276 kN 		64,500–70,000 lbf
287–311 kN 		77,440–91,790 lbf
344–408 kN 		91,790–99,040 lbf
408–441 kN
Variant -94[40] -100[41] -112[42]
Fan 94 in (239 cm) 100 in (254 cm) 112 in (284 cm)
Bypass ratio 4.8–5:1 4.9:1 5.8–6.4:1
Overall pressure ratio 27.5–32.3 32.0–34.1 34.2–42.8
Fan pressure ratio 1.65–1.80 1.75–1.76 1.70–1.80
Applications B747-400, B767, MD-11
A300-600, A310 		A330 B777

See also

[edit]

Related development

Comparable engines

Related lists

References

[edit]

Further reading

[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Pratt & Whitney PW4000

View on Grokipedia
from Grokipedia
The Pratt & Whitney PW4000 is a family of high-bypass aircraft engines manufactured by , introduced as a successor to the JT9D series to provide enhanced , , and reduced noise and emissions for widebody commercial airliners. Launched in 1982, the PW4000 program achieved FAA certification in 1986 and entered commercial service in June 1987, with its first flight occurring in 1985 aboard a testbed. The engine family incorporates advanced technologies such as , single-crystal materials in the high-pressure , and low-emissions combustors, enabling superior performance retention and compliance with stringent noise and environmental regulations. The PW4000 series comprises three primary variants distinguished by fan diameter and thrust ratings. The PW4000-94, with a 94-inch fan and range of 52,000 to 62,000 pounds, was the inaugural model and powers aircraft including the , , , , , and . The PW4000-100, featuring a 100-inch fan and 64,500 to 70,000 pounds of , was certified in 1993 and developed specifically for the , marking the first engine to receive ETOPS approval prior to entering service in 1994. The PW4000-112 (also known as the PW4000 Growth), with a larger 112-inch (9.3-foot) fan and up to 98,000 pounds, entered service in 1995 on the , boasting a of 6.4:1 and pressure ratio of 42.8:1. The variants are approved for extended-range twin-engine operational performance (ETOPS) of up to 207 minutes, depending on the and operational approvals, and have accumulated extensive operational experience, with the PW4000-94 alone logging over 150 million flight hours across more than 2,500 delivered units as of December 2022. The family powers a diverse fleet of worldwide, serving over 70 customers in 30 countries as of 2022, contributing to its reputation for reliability, low maintenance costs, and adaptability in both commercial and military applications.

Development and History

Early Development

The Pratt & Whitney PW4000 was conceived in the early 1980s as the direct successor to the JT9D, the pioneering high-bypass turbofan that had powered wide-body airliners since the late 1960s. Launched in December 1982, the PW4000 family aimed to advance high-bypass efficiency for next-generation wide-body aircraft, incorporating a dual-spool, axial-flow design to deliver improved performance in the competitive market for large commercial jets. Development focused on a thrust range of 50,000 to 99,000 lbf to rival the General Electric CF6 and engines, which dominated the segment for aircraft like the and 767. Key initial design goals emphasized reductions in fuel burn by approximately 7% compared to the JT9D, alongside lower noise and emissions to meet evolving regulatory standards and airline demands for more efficient operations. The program achieved its first ground run in April 1984, marking the start of extensive testing. This was followed by the inaugural in August 1985 on a flying testbed, validating the engine's core technologies under real-world conditions ahead of further refinement.

Certification and Entry into Service

The PW4000-94 variant received (FAA) type certification in July 1986, marking the culmination of extensive testing and validation to meet rigorous safety and performance standards for high-bypass engines. This certification enabled the engine's commercial deployment, positioning it as a competitive option against rivals like the General Electric CF6 and in the widebody market. The PW4000 entered revenue service in June 1987 with on the ; Korean Air was one of the engine's earliest adopters on the A300-600, helping demonstrate its reliability in demanding long-haul operations. Initial applications expanded to other widebody platforms, including the and 767, with first deliveries occurring in 1989—such as to for its 747-400 fleet. These integrations underscored the PW4000's versatility across twin- and four-engine configurations, supporting efficient transoceanic routes. In its first year of operation, the PW4000 demonstrated strong early performance, achieving a dispatch reliability rate exceeding 99%, which reflected its robust design and minimal unscheduled removals during initial fleet integrations. This high reliability was later refined to 99.96% across broader service.

Production and Upgrades

Production of the Pratt & Whitney PW4000 engine family began following its entry into service in 1987, with manufacturing primarily conducted at the company's headquarters and main facility in . By 2017, more than 2,500 engines had been delivered to operators worldwide, and production has continued without interruption into 2025 to support ongoing demand from commercial and military applications. A key upgrade program for the PW4000 series is the Advantage70 initiative, launched in 2006, which incorporates enhancements to the high-pressure and components for improved efficiency. This program delivers a 2% increase in and more than 1% reduction in fuel burn compared to baseline models, along with greater durability to extend time on wing. Offered as both new engines and retrofit kits, Advantage70 has been adopted by operators seeking to lower operating costs without major redesigns. No significant performance upgrade programs have been introduced since 2020, though continues to implement maintenance and safety enhancements, including fan blade inspections and redesigns mandated by regulatory authorities. The PW4000 family had accumulated over 135 million flight hours by , demonstrating its reliability across diverse fleets. By late , the PW4000-94 variant alone exceeded 150 million flight hours, with the overall series continuing to log substantial additional hours through 2025.

Design

Architecture

The Pratt & Whitney PW4000 is a dual-spool, high-bypass ratio engine designed for widebody commercial aircraft. In this configuration, the engine features two independent coaxial spools that rotate at different speeds to optimize and . The low-pressure spool comprises the single-stage fan, the low-pressure (also known as the booster), and the low-pressure , which together handle the majority of the airflow and power the fan to generate . The high-pressure spool includes the high-pressure , the annular , and the high-pressure , which compresses core air, adds fuel for , and extracts energy to drive the . The PW4000 family's fan diameters vary by variant at 94 inches, 100 inches, or 112 inches to accommodate different requirements while maintaining aerodynamic efficiency. This high-bypass design achieves a of approximately 5:1 to 6:1, directing a significant portion of around the core to enhance and reduce . Physically, the engine measures approximately 11 to 16 feet (3.3 to 4.9 meters) in overall length from to and has a dry weight ranging from approximately 9,400 to 15,700 pounds (4,270 to 7,140 kg), depending on the specific model and configuration. Across the family, output spans roughly 50,000 to 100,000 pounds to power various twin- and airliners.

Technologies and Features

The PW4000 series incorporates a Full Authority Digital Engine Control (FADEC) system, which optimizes engine operation by precisely managing fuel flow, variable geometry, and thrust settings for improved and reliability across all variants. Advanced materials, including single-crystal superalloys in the high-pressure blades, enable the to withstand extreme temperatures while enhancing and overall performance. The Talon annular , featuring segmented liner panels and air-blast fuel nozzles for superior fuel atomization and mixing, reduces emissions compared to earlier designs, helping the PW4000 meet stringent environmental standards. Noise levels are mitigated through design elements such as high-bypass ratios and optimized fan blades, achieving significant reduction relative to predecessors like the JT9D and complying with early Stage 3 noise regulations. The engine demonstrates exceptional reliability, with a dispatch rate of 99.96% and an average on-wing time of 13,500 flight hours before requiring a shop visit (as of 2000).

Variants

PW4000-94

The PW4000-94 is the inaugural variant of the Pratt & Whitney PW4000 high-bypass engine family, featuring a 94-inch (2.39 m) fan . Developed as the first model in the series, it received FAA certification in 1986 and entered revenue service in June 1987, powering its initial application on an A310-300 delivered to . Over 2,500 units have been produced since its introduction, accumulating more than 150 million flight hours across a global fleet serving over 70 operators. This variant delivers a thrust range of 52,000 to 62,000 lbf (231 to 276 kN), making it suitable for requiring reliable power for transoceanic routes. It powers five primary aircraft types: the , Boeing 767-200/-300/-400, Airbus A300-600, Airbus A310-300, and McDonnell Douglas MD-11. These applications span passenger and freighter configurations, with the engine certified for 180-minute Extended-range Twin-engine Operational Performance Standards (ETOPS) on twinjets like the 767 and A310. Optimized for medium- to long-haul operations on twin- and four-engine widebodies, the PW4000-94 emphasizes efficiency and durability in both commercial and cargo roles. Like other PW4000 models, it employs for enhanced performance management and reduced pilot workload.

PW4000-100

The PW4000-100 is the 100-inch fan variant of the PW4000 high-bypass engine family, designed exclusively for powering the twin-engine widebody airliner. It provides a thrust range of 64,500 to 70,000 lbf (287 to 311 kN), enabling efficient performance on medium- to long-haul routes with an emphasis on fuel economy and reliability for the A330's operational profile. This variant incorporates advanced aerodynamic features and materials to optimize efficiency for the A330's medium-haul missions, distinguishing it from higher-thrust siblings suited to larger aircraft like the 777. Development of the PW4000-100 began in December 1991 as part of Pratt & Whitney's effort to secure a competitive position on the against the General Electric CF6-80E1. The engine achieved FAA certification in August 1993, followed by its first flight in October 1993, and entered revenue service in December 1994 with and operators like . A key focus during development was enhancing suitability for extended twin-engine operations (ETOPS), with initial 90-minute ETOPS approval at entry into service—the first for a on a twin-engine widebody—and subsequent upgrade to 180-minute ETOPS in July 1995. The primary applications for the PW4000-100 are the A330-200 and A330-300 current engine option (ceo) variants, where it has powered hundreds of aircraft for airlines worldwide, supporting routes up to 7,500 nautical miles. Within this class, the PW4168A model represents a significant , delivering up to 68,000 lbf with a 4.5% increase for hot-and-high conditions while maintaining compatibility with existing A330 fleets through retrofit kits. This , part of the broader Advantage70 program, further improves time-on-wing and reduces maintenance costs for operators. The engine's design, including its wide-chord fan and advanced combustor technologies, contributes to its ETOPS enhancements, ensuring safe and reliable transoceanic operations on twin-engine platforms.

PW4000-112

The PW4000-112 is the highest-thrust variant in the PW4000 family, featuring a 112-inch (2.84 m) fan diameter designed specifically for the 's long-range requirements. It delivers thrust in the range of 74,000 to 99,040 lbf (329 to 441 kN), enabling efficient performance on ultra-long-haul routes. This variant includes the PW4098 model, rated at 98,000 lbf (436 kN), which was discontinued after entering service. Development of the PW4000-112 began in the early as part of the engine competition for the Boeing 777 launch, with selected alongside GE and Rolls-Royce to provide options for the aircraft. The PW4084, the initial -112 model rated at 84,000 lbf (374 kN), achieved its first flight in November 1993 and received FAA certification in April 1994, entering service in May 1995 on a Boeing 777-200. Despite its selection for the 777 program, the variant encountered initial reliability challenges, particularly with the higher-thrust PW4098 certified in July 1998 and introduced in September 1999, which faced operational issues leading to its phase-out. The PW4000-112 powers the 777-200, 777-200ER, and 777-300 "Classic" variants, providing the necessary for extended-range operations while supporting 180-minute ETOPS from entry into service. As the largest fan variant in the PW4000 series, it incorporates such as single-crystal blades for enhanced durability in high- environments. Its design emphasizes , with a separable fan case for easier and , making it suitable for the demanding ultra-long-haul missions of the 777 fleet.

Operational History

Aircraft Applications

The Pratt & Whitney PW4000 engine family powers a diverse range of , including the , (including the military KC-46 tanker variant), Boeing 777-200/-200ER/-300, , A300-600, Airbus A310-300, and A330-200/-300. The PW4000-94 variant equips the , 767, MD-11, A300-600, and A310-300; the PW4000-100 serves the A330; and the PW4000-112 is used on the 777 models. As of 2023, the PW4000 powers over 1,000 in commercial service worldwide, with more than 2,500 engines delivered since 1987 and approximately 1,500 remaining active, serving over 70 operators across 30 countries. These include legacy freighters still operating in cargo roles. Major operators include , which maintains a fleet of 52 Boeing 777s equipped with the PW4000-112. Cargo carriers such as UPS and rely heavily on the PW4000-94 for their fleets, with UPS operating 52 Airbus A300s, 94 Boeing 767s, and 25 MD-11s (many PW-powered) and managing 58 A300s, approximately 160 767s, and 26 MD-11s (similarly equipped) as of late 2025. is the largest passenger operator of PW4000-equipped Boeing 767s, with 58 aircraft in service as of September 2025. The engines support diverse applications, from passenger transport on s and 767s to cargo operations on MD-11 freighters and converted 747-400s, as well as experimental platforms like the Stratolaunch Roc carrier aircraft, which uses six PW4056 engines. In November 2025, following a fatal MD-11 crash in Louisville, UPS and temporarily grounded their PW4000-powered MD-11 fleets for safety inspections. Retirement trends show phasing out on older 747-400s due to fleet modernization, while use remains sustained on Classics for long-haul routes.

In-Service Performance

The PW4000 series has demonstrated exceptional reliability in operational use, achieving a dispatch reliability rate of 99.96%. This high rate reflects the engine's robust design and has contributed to its accumulation of over 150 million flight hours since entering service in 1987, with the PW4000-94 alone surpassing 150 million as of 2022. The average time on wing before a shop visit is approximately 13,500 flight hours, corresponding to a shop visit rate of 0.073 per thousand hours. In terms of , the PW4000 has provided 1-2% improvement over contemporary competitors like the GE CF6 and in its initial service years, owing to its advanced high-bypass ratio architecture. Subsequent upgrades, such as the Advantage 70 package, have further enhanced performance by delivering more than 1% reduction in specific fuel consumption through optimized staging and reduced tip clearances. Maintenance costs for the PW4000 have been favorably impacted by post-upgrade improvements, achieving a shop visit rate of 0.076 per thousand hours—the lowest in its history among similar engines—leading to extended intervals between overhauls and lower overall lifecycle expenses. The segmented liner design of the TALON combustor further supports cost efficiency by enabling easier replacement of components during shop visits. Environmentally, the PW4000 complies with ICAO Stage 4 noise standards, with noise levels reduced by 5-8 EPNdB through advanced acoustic liners and fan blade technologies. Emissions are minimized via the TALON combustor, which incorporates air-blast fuel nozzles to achieve lower levels while meeting CAEP/6 regulatory limits, contributing to reduced overall environmental footprint in service.

Safety and Incidents

Notable Incidents

The PW4000-94 variant experienced several uncontained engine failures in the , primarily attributed to fractures in the low-pressure turbine S3 and S4 vanes as well as 5th-stage compressor blades, leading to case punctures and in-flight shutdowns. These incidents prompted early inspections after cracks were discovered in multiple engines during routine checks. On February 20, 2021, a Longtail Aviation 747-400BCF (Flight 5504) suffered a contained failure of its No. 1 PW4056 engine shortly after takeoff from , , with blade fragments and other parts detaching and falling to the ground near Meerssen, injuring two people and damaging property. The aircraft diverted safely to , , with no further damage to the plane. The PW4000-100 series saw a fan blade separation on March 28, 2022, aboard Flight 134, a 767-300ER en route from Newark to Zurich, when the right PW4060 engine failed over the Atlantic Ocean, causing damage to the right elevator. The crew diverted to Shannon, , landing safely with all 195 passengers and crew uninjured. For the PW4000-112 variant, a fan blade fractured on February 13, 2018, on United Airlines Flight 1175, a Boeing 777-200 en route from San Francisco to Honolulu, resulting in the loss of the inlet cowl and fan blades during climb. The aircraft returned safely to San Francisco with 378 people aboard. On December 4, 2020, Japan Airlines Flight 904, a Boeing 777-200 departing Naha Airport, Okinawa, experienced a left PW4077 engine malfunction at around 16,000 feet, involving blade damage and loss of the engine panel, leading to a safe return. The most severe incident occurred on February 20, 2021, when United Airlines Flight 328, a Boeing 777-200, suffered a right PW4077 fan blade separation shortly after takeoff from Denver, causing an engine fire and debris fallout over a neighborhood. The plane returned safely to Denver with 241 people on board. These events, including the 2018 and 2021 United incidents, involved blade material fatigue as a contributing factor. No major PW4000 incidents were reported from 2023 through 2025.

Investigations and Regulatory Actions

The National Transportation Safety Board (NTSB) issued its final report in September 2023 on the 2021 uncontained failure of a PW4000-112 fan blade during United Airlines Flight 328, attributing the event to metal fatigue that initiated a crack in the blade and propagated undetected over multiple flight cycles. The report highlighted inadequate inspection methods and insufficient frequency of checks, which failed to identify low-level cracking in the blade's midspan region, marking this as the fourth such PW4000-112 fan blade separation incident investigated by the NTSB since 1991. Contributing factors included the engine's design limitations in containing debris and fire propagation, as the failure of the "K" flange allowed hot combustion gases to breach the nacelle. In response to the incident, the (FAA) issued an emergency airworthiness directive on February 21, 2021, mandating the immediate grounding of all aircraft equipped with PW4000-112 engines worldwide until ultrasonic and other inspections could verify blade integrity. This action affected approximately 130 aircraft operated by airlines including United, , and , with return-to-service requirements including enhanced fluorescent penetrant and ultrasonic inspections for all fan blades. By late 2021, the FAA approved temporary exemptions allowing phased returns to service, contingent on ongoing fleet-wide inspections that subsequently identified additional cracked blades. Recent regulatory developments include and Boeing's August 2025 requests to the FAA for exemptions from certain blade-out testing requirements and an extension of the March 4, 2028, deadline for implementing redesigned fan blades and related hardware modifications to 2033, citing technical complexities in validation and issues. These redesigns aim to strengthen blade materials against fatigue and improve features, with phased implementation beginning in 2023 through service bulletins. Enhanced ultrasonic techniques, developed post-incident, now target flowpath surfaces and midspan areas with greater sensitivity to detect subsurface cracks earlier. A 2025 disagreement emerged between the FAA and Dutch investigators regarding the risk assessment of PW4000 failure scenarios tied to the 2021 event, with the FAA reaffirming that potential collateral damage from uncontained failures does not necessitate immediate mandatory redesigns beyond existing directives. The Dutch Safety Board, building on its 2023 recommendations, expressed concerns that regulators may undervalue ground safety risks from debris dispersion, urging more stringent evaluations of failure propagation. This discord highlights ongoing international scrutiny of PW4000 maintenance protocols.

Specifications

PW4000-94 Specifications

The PW4000-94 is a dual-spool, high-bypass designed for widebody commercial , featuring and full-authority digital control () for optimized performance and reliability. It incorporates a single-stage fan with a of 94 inches (2.39 m), enabling efficient airflow in high-thrust applications. The delivers takeoff thrust ranging from 52,000 to 62,000 lbf (231 to 276 kN), supporting operations on such as the and 767-300. The compressor configuration consists of a 1-stage fan, followed by a 4-stage low-pressure (LPC) and an 11-stage high-pressure (HPC), which together achieve an overall of approximately 27.5 to 32.3. This axial-flow arrangement enhances compression efficiency while maintaining a of 4.8 to 5.1, contributing to the engine's fuel economy and low noise profile. The turbine section features a 2-stage high-pressure turbine (HPT) driving the HPC and a 4-stage low-pressure turbine (LPT) powering the fan and LPC, utilizing single-crystal blades for high-temperature durability. The annular employs TALON low-NOx technology to reduce emissions.
ParameterSpecification
TypeDual-spool high-bypass
Length (flange to flange)132.7 in (3.37 m)
Fan Diameter94 in (2.39 m)
Dry Weight9,420 lb (4,273 kg)
Thrust Range52,000–62,000 lbf (231–276 kN)
Compressor Stages1-stage fan, 4-stage LPC, 11-stage HPC
Turbine Stages2-stage HPT, 4-stage LPT
4.8–5.1
Overall Pressure Ratio27.5–32.3

PW4000-100 Specifications

The PW4000-100 is a dual-spool, high-bypass engine designed specifically for such as the A330. It features a large-diameter fan to optimize , contributing to its efficiency in the 64,500–70,000 lbf (287–311 kN) class. Introduced in 1994, this variant emphasizes reliability and ETOPS-180 certification for extended twin-engine operations. Key architectural elements include a 100 in (2.54 m) fan diameter, which supports the engine's high-bypass of approximately 5:1. The configuration comprises a 1-stage fan, 5-stage low-pressure , and 11-stage high-pressure , enabling efficient air compression across varying flight conditions. Downstream, the assembly consists of a 2-stage high-pressure and 5-stage low-pressure , driving the spools while managing thermal loads. The engine's dry weight is approximately 12,900 lb (5,851 kg), balancing performance with installation requirements.
SpecificationDetails
TypeDual-spool high-bypass
Length (flange to flange)163.1 in (4.14 m)
Fan Diameter100 in (2.54 m)
Dry Weight12,900 lb (5,851 kg)
Thrust (Takeoff)64,500–70,000 lbf (287–311 kN)
Compressor1-stage fan, 5-stage LP, 11-stage HP
Turbine2-stage HP, 5-stage LP
Bypass Ratio4.9–5.1
The Advantage70 upgrade enhances thrust by up to 2% while reducing maintenance intervals.

PW4000-112 Specifications

The PW4000-112 is a dual-spool, high-bypass ratio engine designed for ultra-high-thrust applications, primarily powering such as the series. It features advanced aerodynamic and materials technologies to achieve high efficiency and reliability in long-haul operations. Key specifications for the PW4000-112 variant include the following:
ParameterSpecification
TypeDual-spool high-bypass
Fan diameter112 in (2.84 m)
Thrust range74,000–98,000 lbf (330–436 kN)
Compressor1-stage fan, 6-stage low-pressure (7-stage for PW4098 model), 11-stage high-pressure
Turbine2-stage high-pressure, 7-stage low-pressure
Length (flange to flange)191.7 in (4.87 m; ~16 ft)
Dry weight15,584 lb (7,070 kg)
Bypass Ratio5.8:1 to 6.4:1
These parameters reflect the engine's configuration optimized for maximum takeoff thrust in the 777 family, with variations in low-pressure compressor stages for higher-thrust sub-variants like the PW4098.

References

  1. https://airinsight.com/the-pw4000-engine-family/
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  53. https://engineering.purdue.edu/~propulsi/propulsion/jets/tfans/pw4000.html
  54. https://filecache.mediaroom.com/mr5mr_prattwhitney/180694/download/ce_pw4000_100_pCard.pdf
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